With the trend of electronic products getting thinner and being multi-functional, the integration density and the operation speed of semiconductor devices used in a functional circuit of an electronic product are becoming higher. On the other hand, the performance of a shrunken down semiconductor device used in the functional circuit is subject to being negatively affected by current leakage or signal noise. One of the examples of such semiconductor device is a Schottky diode which is commonly used in a functional circuit of a switching-mode power supply. The Schottky diode is a semiconductor device configured with a metal-semiconductor junction, which has a switching speed faster than a switching speed of a conventional p-n rectifier diode. Therefore, the use of the Schottky diode in a functional circuit facilitates higher operation speed of the functional circuit, and thus the integration density of the semiconductor devices included in the functional circuit can thereby be enhanced. However, the Schottky diode has disadvantages including of having a relatively low reverse bias voltage and a relatively high reverse leakage current. In addition, as the reverse leakage current dramatically increases with the raise of temperature, the Schottky diode is likely burned out at elevated temperature. The above problems limit the application of the Schottky diode to a variety of functional circuits.